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Acta Cryst. (2008). E64, m45    [ doi:10.1107/S1600536807063386 ]

Substitutional disorder in a hypervalent diorganotin(IV) dihalide

A. Rotar, R. A. Varga and C. Silvestru

Abstract top

The structure of bromidochloridobis[2-(dimethylaminomethyl)phenyl]tin(IV), [SnBr0.65Cl1.35(C9H12N)2], contains two 2-(Me2NCH2)C6H4 units bonded to a Sn atom which lies on a twofold axis. The compound exhibits substitutional disorder of the halide atoms bonded to the Sn, with 1.35 occupancy for Cl and 0.65 for Br; it is isomorphous with the corresponding dichloride. The Sn atom is hexacoordinated with a (C,N)2SnX2 (X = Cl/Br) distorted octahedral core as a result of the strong intramolecular N[rightwards arrow]Sn coordination trans to the Sn-X bonds (N1-Sn1-X1 = 165.8°). As a result of the intermolecular contacts, viz. H...X and H...benzene interactions, the molecules are arranged in a three-dimensional supramolecular manner in the crystal structure.

Comment top

During our work on hypervalent organotin(IV) compounds with the [2-(Me2NCH2)C6H4]Sn fragment (Varga et al., 2001, 2005, 2006, 2007, Rotar et al. 2007), the title compound (I) was isolated. It contains two 2-(Me2NCH2)C6H4 units bonded to a tin atom which lies on a twofold axis of the space group C2/c. The compound exhibits substitutional disorder of both halide atoms bonded to the Sn with chlorine being the major (1.35) and the bromine the minor (0.65) component.

The structure of [2-(Me2NCH2)C6H4]2SnCl2 was also determined (Varga et al., 2001) and is isomorphous with the title compound. Both have space group C2/c; the cell constants as well as the volume differ slightly (0.39% increase for the title compound) as the result of the presence of a different halide in the molecular unit.

The molecules of the compound feature a metal atom strongly coordinated by two nitrogen atoms of the pendant arms [Sn—N1 = 2.64 (1) Å; the Sn—N distance exceeds the sum of the covalent radii for the corresponding atoms, Σcov(Sn,N) = 2.1 Å (Emsley, 1994)] trans to an Sn–halogen bond (N1—Sn1—X1 = 165.8°). This results in a (C,N)2SnX2 (X = Cl/Br) core in the title compound with a trans-SnC2 fragment, while the N and X atoms are cis positions (Fig. 1). The octahedral geometry around the Sn atom is distorted from the ideal geometry as a consequence of the small 'bite' of the pendant arm ligand [C1—Sn1—N1 = 71.4°] and the steric repulsion between the organic groups bonded to the Sn atoms. All these features are similar to the corresponding dichloride.

As a result of the intramolecular coordination of the nitrogen to the tin atom a five-membered SnC3N ring is formed. This ring is not planar but is folded along the Sn(1)···Cmethylene axis with the N atom out of the best plane defined by the residual SnC3, thus inducing planar chirality, with the phenyl ring as chiral plane and the nitrogen as pilot atom (IUPAC, 1979). Indeed, the compound crystallizes as a racemate, i.e. a mixture of RN1RN1i and SN1SN1i [symmetry code: (i) 2 - x, y, 0.5 - z].

In the crystal of the title compound intermolecular interactions, i.e. hydrogen bond type interactions and H···phenyl interactions (Fig. 2), give rise to a supramolecular array. If only chlorine is considered than layers are built of the same type of isomer [H4···X1ii = 2.87 Å, H3···Cg1ii = 3.19 Å; symmetry code: (ii) -1/2 + x, 1/2 + y, z] along the ab plane (Fig. 3). If bromine is taken into account, than alternating parallel layers of RN1RN1i and SN1SN1i isomers are bridged through weak H6···X1iii [3.02 Å; symmetry code: (iii) 2 - x, 1 - y, 1 - z] interactions resulting in a three-dimensional supramolecular architecture (Fig. 4).

Related literature top

For related literature see Varga et al. (2001, 2005, 2006, 2007); Rotar et al. (2007); Emsley (1994); IUPAC (1979).

Experimental top

The title compound was isolated as a by-product of the reaction between [2-(Me2NCH2)C6H4]SnCl2 and [2,6-(Me)2C6H3]MgBr, due to partial halide exchange.

Refinement top

All hydrogen atoms were placed in calculated positions using a riding model, with C—H = 0.93–0.97 Å and with Uiso= 1.5Ueq (C) for methyl H and Uiso= 1.2Ueq (C) for aryl H. The methyl groups were allowed to rotate but not to tip. The two halide atoms were refined as substitutional disorder between chlorine and bromine, with 1.35 occupancy for Cl and 0.65 occupancy for Br.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART (Bruker, 2000); data reduction: SAINT-Plus (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2001); program(s) used to refine structure: SHELXTL (Bruker, 2001); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures top
[Figure 1] Fig. 1. : A view of title compound showing the atom-numbering scheme at 30% probability thermal ellipsoids for (RN,RNi)-(I) isomer [symmetry code: (i) 2 - x, y, 0.5 - z]. H atoms are drawn as spheres of arbitrary radii.
[Figure 2] Fig. 2. : Intermolecular interactions [shown as dashed lines, black for H···X (X = Cl/Br), red for H···phenyl]. Only H involved in interactions are showed. Symmetry codes: (i) 2 - x, y, 0.5 - z, (ii) -1/2 + x, 1/2 + y, z, (iii) 2 - x, 1 - y, 1 - z.
[Figure 3] Fig. 3. : View of the two-dimensional layer formed through H···X and H···phenyl interactions along c axis. Only H involved in interactions are showed.
[Figure 4] Fig. 4. : Crystal packing showing the three-dimensional supramolecular architecture along a axis. Only H involved in interactions are showed.
bromidochloridobis[2-(dimethylaminomethyl)phenyl]tin(IV) top
Crystal data top
[SnBr0.65Cl1.35(C9H12N)2]F000 = 966.8
Mr = 486.89Dx = 1.627 Mg m−3
Monoclinic, C2/cMo Kα radiation
λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3754 reflections
a = 17.0221 (15) Åθ = 2.5–26.9º
b = 8.2387 (7) ŵ = 2.78 mm−1
c = 14.7510 (13) ÅT = 297 (2) K
β = 106.1050 (10)ºBlock, colourless
V = 1987.5 (3) Å30.32 × 0.25 × 0.11 mm
Z = 4
Data collection top
Bruker Smart APEX CCD area-detector
diffractometer		1746 independent reflections
Radiation source: fine-focus sealed tube1693 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.035
T = 297(2) Kθmax = 25.0º
phi and ω scansθmin = 2.5º
Absorption correction: multi-scan
(SAINT-Plus; Bruker, 2000)		h = −19→20
Tmin = 0.452, Tmax = 0.738k = −9→9
6916 measured reflectionsl = −17→17
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.027H-atom parameters constrained
wR(F2) = 0.060  w = 1/[σ2(Fo2) + (0.P)2 + 3.2594P]
where P = (Fo2 + 2Fc2)/3
S = 1.24(Δ/σ)max = 0.001
1746 reflectionsΔρmax = 0.36 e Å−3
108 parametersΔρmin = −0.46 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
[SnBr0.65Cl1.35(C9H12N)2]V = 1987.5 (3) Å3
Mr = 486.89Z = 4
Monoclinic, C2/cMo Kα
a = 17.0221 (15) ŵ = 2.78 mm−1
b = 8.2387 (7) ÅT = 297 (2) K
c = 14.7510 (13) Å0.32 × 0.25 × 0.11 mm
β = 106.1050 (10)º
Data collection top
Bruker Smart APEX CCD area-detector
diffractometer		1746 independent reflections
Absorption correction: multi-scan
(SAINT-Plus; Bruker, 2000)		1693 reflections with I > 2σ(I)
Tmin = 0.452, Tmax = 0.738Rint = 0.035
6916 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.027108 parameters
wR(F2) = 0.060H-atom parameters constrained
S = 1.24Δρmax = 0.36 e Å−3
1746 reflectionsΔρmin = −0.46 e Å−3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Br11.04832 (5)0.42622 (9)0.36987 (5)0.0721 (3)0.325 (3)
Cl11.04832 (5)0.42622 (9)0.36987 (5)0.0721 (3)0.675 (3)
Sn11.00000.64336 (4)0.25000.03453 (12)
C10.89182 (18)0.7072 (4)0.2862 (2)0.0386 (7)
C60.8831 (2)0.6785 (4)0.3757 (2)0.0455 (8)
H60.92540.62930.42120.055*
C20.8274 (2)0.7761 (5)0.2181 (3)0.0517 (9)
C50.8125 (2)0.7221 (5)0.3982 (3)0.0589 (10)
H50.80720.70220.45830.071*
C40.7506 (3)0.7942 (6)0.3318 (3)0.0714 (12)
H40.70350.82600.34720.086*
C30.7572 (2)0.8206 (6)0.2424 (3)0.0707 (12)
H30.71410.86880.19750.085*
N10.91474 (19)0.8322 (4)0.1136 (2)0.0547 (8)
C70.8321 (2)0.7923 (6)0.1177 (3)0.0653 (11)
H7A0.81500.69110.08450.078*
H7B0.79470.87660.08600.078*
C80.9324 (3)1.0031 (5)0.1373 (3)0.0785 (13)
H8A0.89541.07000.09150.118*
H8B0.98761.02690.13710.118*
H8C0.92591.02460.19870.118*
C90.9204 (3)0.8054 (7)0.0157 (3)0.0838 (15)
H9A0.88100.8724−0.02730.126*
H9B0.90960.6934−0.00120.126*
H9C0.97440.83310.01240.126*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0787 (5)0.0714 (5)0.0805 (6)0.0373 (4)0.0458 (4)0.0378 (4)
Cl10.0787 (5)0.0714 (5)0.0805 (6)0.0373 (4)0.0458 (4)0.0378 (4)
Sn10.03419 (18)0.03473 (18)0.04017 (19)0.0000.01949 (13)0.000
C10.0344 (16)0.0371 (17)0.0486 (19)0.0027 (13)0.0187 (15)−0.0014 (14)
C60.0446 (19)0.048 (2)0.050 (2)0.0021 (15)0.0240 (16)−0.0028 (16)
C20.0413 (19)0.061 (2)0.056 (2)0.0070 (17)0.0187 (17)0.0090 (18)
C50.058 (2)0.068 (3)0.063 (2)0.003 (2)0.036 (2)−0.002 (2)
C40.052 (2)0.084 (3)0.093 (3)0.015 (2)0.045 (2)0.002 (3)
C30.044 (2)0.082 (3)0.089 (3)0.018 (2)0.023 (2)0.013 (2)
N10.0518 (18)0.068 (2)0.0470 (17)0.0091 (15)0.0181 (14)0.0161 (15)
C70.045 (2)0.088 (3)0.059 (2)0.009 (2)0.0076 (18)0.019 (2)
C80.090 (3)0.062 (3)0.085 (3)0.004 (2)0.026 (3)0.022 (2)
C90.084 (3)0.121 (4)0.050 (2)0.019 (3)0.024 (2)0.030 (3)
Geometric parameters (Å, °) top
Br1—Sn12.4893 (7)C4—H40.9300
Sn1—C12.121 (3)C3—H30.9300
Sn1—C1i2.121 (3)N1—C71.462 (5)
Sn1—Cl1i2.4893 (7)N1—C81.462 (5)
Sn1—Br1i2.4893 (7)N1—C91.491 (5)
C1—C21.387 (5)C7—H7A0.9700
C1—C61.389 (5)C7—H7B0.9700
C6—C51.380 (5)C8—H8A0.9600
C6—H60.9300C8—H8B0.9600
C2—C31.389 (5)C8—H8C0.9600
C2—C71.510 (5)C9—H9A0.9600
C5—C41.360 (6)C9—H9B0.9600
C5—H50.9300C9—H9C0.9600
C4—C31.372 (6)
C1—Sn1—C1i151.30 (17)C4—C3—C2120.8 (4)
C1—Sn1—Cl1i102.61 (9)C4—C3—H3119.6
C1i—Sn1—Cl1i97.93 (9)C2—C3—H3119.6
C1—Sn1—Br1i102.61 (9)C7—N1—C8110.1 (3)
C1i—Sn1—Br1i97.93 (9)C7—N1—C9109.2 (3)
Cl1i—Sn1—Br1i0.00 (4)C8—N1—C9108.0 (3)
C1—Sn1—Br197.93 (9)N1—C7—C2112.0 (3)
C1i—Sn1—Br1102.61 (9)N1—C7—H7A109.2
Cl1i—Sn1—Br188.11 (4)C2—C7—H7A109.2
Br1i—Sn1—Br188.11 (4)N1—C7—H7B109.2
C2—C1—C6119.2 (3)C2—C7—H7B109.2
C2—C1—Sn1119.1 (2)H7A—C7—H7B107.9
C6—C1—Sn1121.8 (2)N1—C8—H8A109.5
C5—C6—C1120.9 (3)N1—C8—H8B109.5
C5—C6—H6119.6H8A—C8—H8B109.5
C1—C6—H6119.6N1—C8—H8C109.5
C1—C2—C3119.0 (4)H8A—C8—H8C109.5
C1—C2—C7120.0 (3)H8B—C8—H8C109.5
C3—C2—C7120.9 (3)N1—C9—H9A109.5
C4—C5—C6119.6 (4)N1—C9—H9B109.5
C4—C5—H5120.2H9A—C9—H9B109.5
C6—C5—H5120.2N1—C9—H9C109.5
C5—C4—C3120.5 (4)H9A—C9—H9C109.5
C5—C4—H4119.7H9B—C9—H9C109.5
C3—C4—H4119.7
C1i—Sn1—C1—C270.1 (3)C6—C1—C2—C7−173.7 (4)
Cl1i—Sn1—C1—C2−64.6 (3)Sn1—C1—C2—C74.9 (5)
Br1i—Sn1—C1—C2−64.6 (3)C1—C6—C5—C4−0.1 (6)
Br1—Sn1—C1—C2−154.4 (3)C6—C5—C4—C31.5 (7)
C1i—Sn1—C1—C6−111.4 (3)C5—C4—C3—C2−0.8 (7)
Cl1i—Sn1—C1—C6113.9 (3)C1—C2—C3—C4−1.3 (7)
Br1i—Sn1—C1—C6113.9 (3)C7—C2—C3—C4175.0 (4)
Br1—Sn1—C1—C624.1 (3)C8—N1—C7—C2−75.8 (4)
C2—C1—C6—C5−2.0 (5)C9—N1—C7—C2165.8 (4)
Sn1—C1—C6—C5179.5 (3)C1—C2—C7—N1−37.0 (5)
C6—C1—C2—C32.6 (6)C3—C2—C7—N1146.8 (4)
Sn1—C1—C2—C3−178.8 (3)
Symmetry codes: (i) −x+2, y, −z+1/2.
Table 1
Y—H···π-ring interactions. top
Y—H···CgY—HH···CgY···CgY—H···Cg
C3—H3···Cg1ii0.933.193.78 (1)123
Symmetry code: (ii) -1/2 + x, 1/2 + y, z. Cg1 is the centroid of the benzene ring C1–C6.
Table 2
Hydrogen-bond geometry (Å, °) top
D-H···AD-HH···AD···AD-H···A
C4-H4···Cl1ii/Br1ii0.932.873.798 (5)173
C6-H6···Cl1iii/Br1iii0.933.023.710 (3)132
Symmetry code: (ii) -0.5+x, 0.5+y, z, (iii) 2-x, 1-y, 1-z.
Acknowledgements top

Financial support from National University Research Council (CEEX 63/2006) is greatly appreciated. We also thank the National Center for X-Ray Diffraction from Cluj-Napoca for the support with the solid-state structure determination.

references
References top

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Emsley, J. (1994). Die Elemente. Berlin: Walter de Gruyter.

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